1. Field of the Invention
In general, the present invention relates to an infrared signal transmitting apparatus. In particular, the present invention relates to an infrared signal transmitting apparatus which is connected to a computer and used for exchanging high-speed signals with the computer by using infrared signals as well as transmitting low-speed signals from the computer by using infrared signals each having a wide directivity.
2. Description of the Related Art
In general, an infrared signal transmitting apparatus is used in connection with a computer by a wire. The infrared signal transmitting apparatus typically comprises a single infrared light emitting device for transmitting high-speed signals, a single light receiving device for receiving high-speed signals and a plurality of infrared light emitting devices for transmitting low-speed signals which are distributed and laid out in such a way that, as a whole, a wide directivity is obtained. The infrared light emitting device for transmitting high-speed signals transmits a high-speed signal such as a data signal received from the wire-connected computer to another computer or another kind of equipment as an infrared signal. The light receiving device for receiving high-speed signals receives an infrared signal transmitted by another computer and transmits the infrared signal to the wire-connected computer as a data signal. The infrared light emitting devices for transmitting low-speed signals are each used for transmitting a low-speed signal received from the wire-connected computer such as a remote-control signal to a television (TV) or a video tape recorder (VTR) as an infrared signal. The remote-control signal is used for remotely controlling the television or the video tape recorder.
FIG. 2 is a perspective view of a typical configuration of the conventional infrared signal transmitting apparatus. FIG. 3 is a block configuration diagram showing a typical internal configuration of the conventional infrared signal transmitting apparatus shown in FIG. 2.
As shown in FIG. 2, the conventional infrared signal transmitting apparatus 20 comprises a cabinet 21 having substantially a rectangular parallelopiped shape with four side surfaces in addition to top and bottom surfaces to give a total of six surfaces, a infrared light emitting device 22 for transmitting high-speed signals and a light receiving device 23 for receiving high-speed signals provided on one of the side surfaces at the same altitude, first to third infrared light emitting devices 24, 25 and 26 for transmitting low-speed signals provided on the respective three remaining side surfaces. The infrared signal transmitting apparatus 20 is connected to a computer 28 by a wire 27. Data is exchanged between the computer 28 and another computer 29 such as a notebook personal computer located in close proximity to the computer 28 with infrared signals.
As shown in FIG. 3, the infrared signal transmitting apparatus 20 also has a controller 30, a high-speed-signal modulating/demodulating circuit 31, a high-speed-signal driving circuit 32, a high-speed-signal receiving circuit 33, a low-speed-signal demodulating circuit 34 and a low-speed-signal driving circuit 35 in addition to the infrared light emitting device 22, the light receiving device 23 and the first to third infrared light emitting devices 24, 25 and 26 shown in FIG. 2.
The controller 30 is connected to the computer 28 by the wire 27 as well as to the input/output terminal of the high-speed-signal modulating/demodulating circuit 31 and to the input terminal of the low-speed-signal demodulating circuit 34. The output terminal of the high-speed-signal modulating/demodulating circuit 31 is connected to the input terminal of the high-speed-signal driving circuit 32 and its input terminal is connected to the output terminal of the high-speed-signal receiving circuit 33. The output terminal of the low-speed-signal demodulating circuit 34 is connected to the input terminal of the low-speed-signal driving circuit 35. The output terminal of the high-speed-signal driving circuit 32 is connected to the infrared light emitting device 22. The input terminal of the high-speed-signal receiving circuit 33 is connected to the light receiving device 23. Finally, the output terminal of the low-speed-signal driving circuit 35 is connected to the first to third infrared light emitting devices 24, 25 and 26 which are connected in series.
The infrared signal transmitting apparatus 20 with the configuration described above operates as follows.
First of all, in the case of an exchange of data between the computer 28 and the other computer 29, the computer 28 supplies the infrared signal transmitting apparatus 20 with a transmission signal including data to be transmitted to the other computer 29 by way of the connection wire 27. The controller 30 identifies the received transmission signal, supplying it to the high-speed-signal modulating/demodulating circuit 31. The high-speed-signal modulating/demodulating circuit 31 demodulates the transmission signal and the modulated signal is supplied to the high-speed-signal driving circuit 32. The high-speed-signal driving circuit 32 drives the infrared light emitting device 22 for transmitting high-speed signals in accordance with the demodulated signal. The infrared light emitting device 22 transmits a first infrared signal including the data signal to the other computer 29.
When a second infrared signal including a data signal is transmitted by the other computer 29 to the infrared signal transmitting apparatus 20, on the other hand, the light receiving device 23 for receiving high-speed signals receives the second infrared signal. The high-speed-signal receiving circuit 33 generates an electrical signal representing the second infrared signal, supplying the electrical signal to the high-speed-signal modulating/demodulating circuit 31. The high-speed-signal modulating/demodulating circuit 31 modulates the electrical signal supplied thereto, converting it into a transmission signal which is then supplied to the controller 30. The controller 30 identifies the transmission signal supplied thereto, transmitting it to the computer 28 by way of the connection wire 27.
In this way, data is exchanged between the computer 28 and the other computer 29 by using the first and second infrared signals.
Next, when the computer 28 transmits a remote-control signal to a television or a video tape recorder not shown in the figure, first of all, the computer 28 supplies a transmission signal including the remote-control signal to the infrared signal transmitting apparatus 20 by way of the connection wire 27. The controller 30 identifies the received transmission signal, supplying it to the low-speed-signal demodulating circuit 34. The low-speed-signal demodulating circuit 34 demodulates the transmission signal and the demodulated signal is supplied to the low-speed-signal driving circuit 35. The low-speed-signal driving circuit 35 drives the three first to third infrared light emitting devices 24, 25 and 26 for transmitting low-speed signals in accordance with the demodulated signal. The three first to third infrared light emitting devices 24, 25 and 26 each transmit an infrared signal including the remote-control signal to the television or the video tape recorder. The operation of the television or the video tape recorder is controlled by the remote-control signal.
In the conventional infrared signal transmitting apparatus 20 described above, when an infrared signal conveying a data signal is transmitted, the receiver or transmitter of the infrared signal is specified. For this reason, the infrared light emitting device 22 for transmitting high-speed signals or the light receiving device 23 for receiving high-speed signals has a sharp directivity with respect to the receiver or transmitter of the infrared signal.
When an infrared signal conveying a remote-control signal is transmitted, on the other hand, normally, no receiver of the infrared signal is specified. For this reason, a plurality of infrared light emitting devices for transmitting low-speed signals are required to provide directivities in all directions. In the particular case of the infrared signal transmitting apparatus 20 shown in FIGS. 2 and 3, three devices, that is, the first to third infrared light emitting devices 24, 25 and 26 for transmitting low-speed signals, are employed.
By the way, even if the three devices, that is, the first to third infrared light emitting devices 24, 25 and 26, are employed in the conventional infrared signal transmitting apparatus 20, at the most, the infrared signal transmitting apparatus 20 covers only a transmission range of an infrared signal conveying a remote-control signal for three directions in which the three devices, that is, the first to third infrared light emitting devices 24, 25 and 26, are employed. The infrared signal transmitting apparatus 20 has a problem that the transmission range of an infrared signal conveying a remote-control signal does not cover a direction in which the infrared light emitting device 22 for transmitting high-speed signals and the light receiving device 23 for receiving high-speed signals are provided.
It stands to reason that, if a fourth infrared light emitting device for transmitting low-speed signals is newly installed in the direction in which the infrared light emitting device 22 and the light receiving device 23 are provided, the problem described above can be solved. By installing the fourth infrared light emitting device, however, not only the number of components and the amount of consumed power are increased, but the infrared signal transmitting apparatus 20 also becomes inevitably bigger in size. As a result, the infrared signal transmitting apparatus 20 introduces a new problem that the manufacturing cost thereof also rises as well.